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Alpha One oil leak, loose shift shaft

July 18th, 2010, 05:31 PM

Hello everyone. I am looking for direction in how to fix this problem. I noticed after taking the boat out yesterday that it leaked some oil in the driveway with the drive tilted up. 1986 Alpha one, 230 HP...

It appears to be coming from lower shift rod. The one that slots into the u shaped thing. The U shaped one is solid, however the bottom rod is loose, and has about a 1/4 up and down movement, as well as a small amount of side to side play. In the picture you can see its barely even in its groove. Cant be normal can it? Either way a leak isnt..

So what went wrong, and how do I fix it??? The thing was working/shifting great when I brought it in.

Edit, I checked out how things were on my dads boat, and my other boat, and all of the lower shift rods seemed to have that play in them. So should I even bother being worried about a drop here and there? I'm gonna change gear oil and examine for water intrusion either way...

So what went wrong, and how do I fix it??? The thing was working/shifting great when I brought it in.

No it is not. The intermediate shift shaft sits on a washer on the lower shift shaft. If the washer is missing or bent it will allow the intermediate ss to drop down like yours. You fix it by splitting the outdrive and replacing the washer. Leaking water out of the upper shift shaft would indicate bad shift shaft seals. If gearcase oil, the only place I can think of is from the bellows, past both upper shift shaft seals. Oil in the bellows would indicate a bad driveshaft seal.

Terry
87, 4WINNS H 190
470/Alpha I

Comment

Fair enough, would be a good time to do impeller anyways. And yes, there does seem to be water leaking out of the upper shift shaft as well, I would assume from the exhaust, since that passes right around that shaft. Just water though. And who knows for certain because that pic was taken just a few hours after I pulled it out of water.

But I am 100% positive the gear oil is coming from this intermediate shaft. Sort of odd that a simple washer makes the seal there, but looks like I got some work to do.

Comment

Okay, so today I drained the drive, ( had a small amout of water intrusion ) and pulled the lower unit off. I inspected the shift shaft bushing seal. It appeared to be in good shape, and there was NO evidence of gear oil leaking from it. It was very dry all around. No visible leaks at the water pump area either, and the impeller and housing looked virtually new. Thats all good and well, so I greased the bushings rubber and metal washer, and the shaft splines, and put it back on. Refilled the drive, and now its leaking again. From the same area. However it actually looks like its coming from the upper shift shaft on down. Which to my knowledge its impossible to have gear oil up there. So I dunno if thats just an illusion but either way, im getting frustrated.

Now I've also been lead to believe that a leaking shift shaft bushing seal, or water pump seal will cause gear oil to leak from the weep hole at the bottom of the gearcase. That hasnt happened here. Like I said it was all very dry on the lower unit. No oil anywhere. For how much this thing leaks I expected something.

So is there anything im missing before I get desperate and take the whole drive in to someone?

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Thanks, for some reason I was under the impression that it would only leak into the bellows from there, but looking at the other boat thats already apart here certainly makes a good case if its leaking down the shift shaft.

So aside from the big carrier wrench is there any special tools I'll need? Or is this one best left to the pros? Is the carrier seal pressed on, or is it just a matter of taking the nut off the forward gear and pulling it all apart? The clymer I borrowed is vague, and my pc isnt opening the merc manual from here.

Comment

you need the spanner wrench.Get the unit into a suitable holding device, remove carrier nut and pull assembly from drive making sure the shims do not get lost.sometimes they come out or stay in the housing.Remove nut using a 15/16 wrench,notice the washer says"nut" on it.
pull gears ,bearings, seal, carrier nut off the input yoke. Note the order!!!!!!!!!!!!!!!!!!!!!
press old seal out, press new seal in, re-assemble in reverse order, torque nut to spec, install shaft and tighten carrier nut to spec. Use seal National 712250 .Available at most good auto stores. This is the original OEM seal .

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So far ive been continuously defeated by this stupid drive. I can tell its been on there for quite awhile. Got it all unbolted, and pried the drive back maybe an inch, but its just flat out stuck. I beat, pried, banged on it for three hours this morning. Even went so far as to tie a rope to it and try to pull it with my motorcycle ( probably a first on this forum ). Yes its in forward too BTW.

Either way I got in the engine compartment and sprayed the driveshaft and gimbal bearing with maxfilm. I'm letting that sit and we will see what happens. From what I felt the splines on the driveshaft were well lubed before this so I dunno why it wants a fight? Either way I'm going to pull it off and attempt replacing the lower seal that the lower unit driveshaft slides into as well, it looked like there was oil seepage there too.